The present invention relates to a structural improvement on a carburetor for motorcycles and more particularly to a carburetor provided with an oil re-atomizing device so as to ensure an almost complete atomization of injected gasoline before delivery into a combustion chamber of an engine. Near the middle of a horizontally extended air passage of the carburetor is disposed a section having an increasingly expanded diameter so as to permit a re-atomizing device to be mounted to the end of the section. The re-atomizing device is made up of a cone-shaped head portion and a circular supporting bracket that are fixed together by a screw. Oil sucked into the air passage via a needle controlled oil supply passage is brought into direct collision against the cone-shaped head portion of the re-atomizing device. The bottom of the head portion is provided with a flanged skirt which has a peripheral recess so that the mixture of air and oil will produce eddy current pressure at the flanged skirt, resulting in full and effective atomization of the mixture flow before it enters the combustion chamber of an engine.
Referring to FIG. 1, a first conventional carburetor 10 has a horizontal air passage 11 and a vertical vacuum-operated valve member 12 having a needle 13 disposed at the bottom end of the piston member 12. The piston member 12 partially housed in the air passage 11 is disposed near the front portion of the carburetor. The needle 13 is movably inserted into an oil supply path 15 in communication with an oil reservoir 14 located at the bottom of the carburetor 10. At the rear portion of air passage 11 is placed a throttle valve 16. Air can be led into the air passage 11 from the front end thereof. The speedy flow of air into the air passage 11 results in the suction of gasoline from the oil reservoir 14 into the air passage 11 via the clearance between the needle 13 and the oil supply path 15. As shown in FIG. 2, the supplied gasoline or oil is delivered axially forward along with air in the air passage 11 in atomized particles.
Referring to FIGS. 3, 4, the second prior art carburetor 20 has a horizontal air passage 21 in which an adjustable Venturi-tube 22 including a round-ended cone member 221, a bell-shaped cover 222, a supporting bracket 223, a spring 224 and a central shaft 225 is housed. An oil reservoir 23 is located under the carburetor 20 and 4 nozzles 24 are used to inject oil to the adjustable Venturi-tube 22 from the reservoir 23. In operation, air is introduced into the air passage 21 from the front end thereof, and the injected oil from the 4 nozzles will be guided along the contour of the round-ended cone member 221 of the Venturi-tube 22 so as to make the oil atomized into particles, as shown in FIG. 5.
The above listed prior arts have the following disadvantages: the carburetors 10, 20 can not get the oil atomized effectively, resulting in incomplete combustion of the gasoline injected into combustion chambers of an engine and oil consumption is high in such carburetor-associated engines and air pollution as a result of producing massive amount of carbon monoxide is another serious problem.